chromeos: Remove whitelist of ash prefs for late registration with sync

The "late registration" feature was added to support the mustash
project, which was running the ash system UI in a separate process.
Mustash was cancelled, so we now guarantee that all ash prefs
are registered before the sync subsystem starts.

Remove the whitelist. This is a manual revert of:
https://chromium-review.googlesource.com/c/chromium/src/+/1012788/

The PrefRegistry feature will be cleaned up separately, after
resolving the device_sync service and assistant service usage of
prefs.

Bug: 788918, 1012462
Change-Id: I9811c8f25530d9c0e949ae0675e51aeeb9f583c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1845963
Commit-Queue: James Cook <jamescook@chromium.org>
Auto-Submit: James Cook <jamescook@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#703915}

chrome/browser/chromeos/preferences.cc

@@ -115,25 +115,6 @@ void TryMigrateToResolveTimezoneByGeolocationMethod(PrefService* prefs) {
                     static_cast<int>(method));
 }
 
-// Whitelist synable preferences that may be registered after sync system init.
-void WhitelistLateRegistrationPrefsForSync(
-    user_prefs::PrefRegistrySyncable* registry) {
-  // These foreign syncable preferences are registered asynchronously by Ash,
-  // perhaps after sync system initialization. Whitelist these prefs so that any
-  // values obtained via sync before the prefs are registered will be stored.
-  const char* const kAshForeignSyncablePrefs[] = {
-      ash::prefs::kEnableAutoScreenLock,
-      ash::prefs::kEnableStylusTools,
-      ash::prefs::kLaunchPaletteOnEjectEvent,
-      ash::prefs::kMessageCenterLockScreenMode,
-      ash::prefs::kShelfAlignment,
-      ash::prefs::kShelfAutoHideBehavior,
-      ash::prefs::kTapDraggingEnabled,
-  };
-  for (const auto* pref : kAshForeignSyncablePrefs)
-    registry->WhitelistLateRegistrationPrefForSync(pref);
-}
-
 }  // namespace
 
 Preferences::Preferences()
@@ -184,8 +165,6 @@ void Preferences::RegisterPrefs(PrefRegistrySimple* registry) {
 // static
 void Preferences::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
-  WhitelistLateRegistrationPrefsForSync(registry);
-
   std::string hardware_keyboard_id;
   // TODO(yusukes): Remove the runtime hack.
   if (IsRunningAsSystemCompositor()) {